U.S. Pat. No. 4,610,367 of Massott et al discloses a tamper-proof closure for use with threaded containers. The Massott et al closure comprises a plastic sealing ring which engages a threaded metallic cap and a security ring attached to the collar by means of a multiplicity of fracturable retaining links. When the cap is unscrewed from the container, the links rupture and the security ring drops to provide an indication that the container has been opened. The collar and security ring are such that they can be readily removed from the container which is beneficial if the cap or container is to be recycled.
The Massott et al patent contains a description of various known types of tamper-proof closures and its description of the prior art is hereby incorporated by reference into this specification.
A problem with the closure of the Massott et al patent is that in some circumstances the signal that the container has been opened is not always readily apparent. The present invention is an improvement over the tamper-proof closure shown and described in the Massott et al patent in that it provides a more reliable indicator that the closure has been removed from the container.
French Pat. No. 2,528,393 discloses a security ring which is inserted into the container cap from the inside and hooked onto the cap. When the cap is unscrewed from the bottle, a claw is torn from the attachment part of the security ring and remains hanging on the bottle below the threaded portion. When bottles are to be redeemed, this type of closure is undesirable since the claw remains hanging on the bottle and must be removed laboriously before the bottle can be recycled. Likewise, with respect to the metal cap, the attachment parts of the security ring must be removed since the metal and plastic parts must be separated prior to recycling.
An object of the invention is to avoid these disadvantages and to provide a security device for containers which is easy to manufacture, securely connected with the container closure but which, after use, can be readily separated from both the container and the cap.